+0  
 
0
84
2
avatar

Thanks!

Guest Feb 22, 2018
edited by Guest  Feb 22, 2018
Sort: 

2+0 Answers

 #1
avatar+86613 
+1

Due to symmetry  the x coordinate of the vertex = 5

 

The points  (3,0) (7,0) and (2, - 5)  are on the graph

 

And we have this form

 

y  =  ax^2 + bx + c

 

The x coordinate of the vertex  =  

 

-b / (2a)  =  5

-b  = 10a

b  =  -10a

 

So we have that using  (3,0)

 

0  =  a(3)^2 - 10a(3)  + c

0 =  9a - 30a + c

0  =  - 21a + c

-c = -21a

c = 21a

 

And using  (2, -5)

-5  =  a(2)^2  - 10a(2) + 21a

-5  = 4a - 20a + 21a

-5  = 5a

a  =  -1

 

And b =  -10(-1)  =  10

And c = 21(-1)  = -21

 

So our function is :

 

y = -1x^2 + 10x  - 21

 

Here;s the graph : https://www.desmos.com/calculator/u2qnb8dswx

 

 

cool cool cool

CPhill  Feb 22, 2018
 #2
avatar
0

Thanks so much!

Guest Feb 22, 2018

24 Online Users

avatar
avatar
avatar
New Privacy Policy (May 2018)
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  Privacy Policy